In the past, blenders have been used primarily for preparing foods, and their blades have been adapted for that purpose. Any use of the blender for ice crushing was secondary, with the crushing quality not being a significant design factor.
Various shapes of blender blades have been used. In many cases two pairs of blades would be used, with a first pair angling upward, and a second pair angling downward. Examples of such blades can be found in various United States Patents, such as: Landgraf U.S. Pat. No. 2,309,347; Malz U.S. Pat. No. 2,758,623; Seyfried U.S. Pat. No. 2,771,111; Jepson U.S. Pat. No. 3,175,594; Knapp U.S. Pat. No. 3,036,614; Voglesonger U.S. Pat. No. 4,087,053; and Ernster U.S. Pat. No. 4,462,694. Though many of these patents disclose pairs of blender blades, none disclose the particular structure of my invention which works so well in ice crushing. None discloses a pair of upwardly-extending blades of similar configuration, but at different angles to the axis, and with leading edges which are slightly concave so as to catch and hold ice while crushing it. None discloses such a pair of blades positioned such that one extends upwardly more than the other so that it is the first to hit and crush the ice, while the other, lower blade, serves to continue the chipping.